diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp
index 405628b..5674cb4 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp
@@ -34,7 +34,7 @@
     mFlags = PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(dictBuf, &pos);
     const int parentPos =
             DynamicPatriciaTrieReadingUtils::getParentPosAndAdvancePosition(dictBuf, &pos);
-    mParentPos = (parentPos != 0) ? mNodePos + parentPos : NOT_A_DICT_POS;
+    mParentPos = (parentPos != 0) ? nodePos + parentPos : NOT_A_DICT_POS;
     if (outCodePoints != 0) {
         mCodePointCount = PatriciaTrieReadingUtils::getCharsAndAdvancePosition(
                 dictBuf, mFlags, maxCodePointCount, outCodePoints, &pos);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
index 6d1bd02..2c28da9 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
@@ -47,14 +47,16 @@
         const int nodeCodePointCount = nodeReader->getCodePointCount();
         for (int j = 1; j < nodeCodePointCount; ++j) {
             const int nextIndex = matchedCodePointCount + j;
-            if (nextIndex >= codePointCount) {
-                // TODO: split current node after j - 1, create child and make this terminal.
-                return false;
-            }
-            if (!readingHelper->isMatchedCodePoint(j,
+            if (nextIndex >= codePointCount || !readingHelper->isMatchedCodePoint(j,
                     wordCodePoints[matchedCodePointCount + j])) {
-                // TODO: split current node after j - 1 and create two children.
-                return false;
+                if (ENABLE_DYNAMIC_UPDATE) {
+                    return reallocatePtNodeAndAddNewPtNodes(nodeReader,
+                            readingHelper->getMergedNodeCodePoints(), j, probability,
+                            wordCodePoints + matchedCodePointCount,
+                            codePointCount - matchedCodePointCount);
+                } else {
+                    return false;
+                }
             }
         }
         // All characters are matched.
@@ -136,20 +138,22 @@
             &writingPos)) {
         return false;
     }
-    // Update moved position, which is stored in the parent position field.
-    if (!DynamicPatriciaTrieWritingUtils::writeParentPositionAndAdvancePosition(
-            mBuffer, movedPos, &writingPos)) {
+    // Update moved position, which is stored in the parent offset field.
+    const int movedPosOffset = movedPos - originalNode->getNodePos();
+    if (!DynamicPatriciaTrieWritingUtils::writeParentOffsetAndAdvancePosition(
+            mBuffer, movedPosOffset, &writingPos)) {
         return false;
     }
     return true;
 }
 
-// Write new node at writingPos.
-bool DynamicPatriciaTrieWritingHelper::writeNodeToBuffer(const bool isBlacklisted,
+// Write new PtNode at writingPos.
+bool DynamicPatriciaTrieWritingHelper::writePtNodeWithFullInfoToBuffer(const bool isBlacklisted,
         const bool isNotAWord, const int parentPos, const int *const codePoints,
         const int codePointCount, const int probability, const int childrenPos,
         const int originalBigramListPos, const int originalShortcutListPos,
         int *const writingPos) {
+    const int nodePos = *writingPos;
     // Create node flags and write them.
     const PatriciaTrieReadingUtils::NodeFlags nodeFlags =
             PatriciaTrieReadingUtils::createAndGetFlags(isBlacklisted, isNotAWord,
@@ -160,9 +164,10 @@
             writingPos)) {
         return false;
     }
-    // Write parent position
-    if (!DynamicPatriciaTrieWritingUtils::writeParentPositionAndAdvancePosition(mBuffer, parentPos,
-            writingPos)) {
+    // Calculate a parent offset and write the offset.
+    const int parentOffset = (parentPos != NOT_A_DICT_POS) ? parentPos - nodePos : NOT_A_DICT_POS;
+    if (!DynamicPatriciaTrieWritingUtils::writeParentOffsetAndAdvancePosition(mBuffer,
+            parentOffset, writingPos)) {
         return false;
     }
     // Write code points
@@ -200,6 +205,25 @@
     return true;
 }
 
+bool DynamicPatriciaTrieWritingHelper::writePtNodeToBuffer(const int parentPos,
+        const int *const codePoints, const int codePointCount, const int probability,
+        int *const writingPos) {
+    return writePtNodeWithFullInfoToBuffer(false /* isBlacklisted */, false /* isNotAWord */,
+            parentPos, codePoints, codePointCount, probability,
+            NOT_A_DICT_POS /* childrenPos */, NOT_A_DICT_POS /* originalBigramsPos */,
+            NOT_A_DICT_POS /* originalShortcutPos */, writingPos);
+}
+
+bool DynamicPatriciaTrieWritingHelper::writePtNodeToBufferByCopyingPtNodeInfo(
+        const DynamicPatriciaTrieNodeReader *const originalNode, const int parentPos,
+        const int *const codePoints, const int codePointCount, const int probability,
+        int *const writingPos) {
+    return writePtNodeWithFullInfoToBuffer(originalNode->isBlacklisted(),
+            originalNode->isNotAWord(), parentPos, codePoints, codePointCount, probability,
+            originalNode->getChildrenPos(), originalNode->getBigramsPos(),
+            originalNode->getShortcutPos(), writingPos);
+}
+
 bool DynamicPatriciaTrieWritingHelper::createAndInsertNodeIntoPtNodeArray(const int parentPos,
         const int *const nodeCodePoints, const int nodeCodePointCount, const int probability,
         int *const forwardLinkFieldPos) {
@@ -228,10 +252,8 @@
         if (!markNodeAsMovedAndSetPosition(originalPtNode, movedPos)) {
             return false;
         }
-        if (!writeNodeToBuffer(originalPtNode->isBlacklisted(), originalPtNode->isNotAWord(),
-                originalPtNode->getParentPos(), codePoints, originalPtNode->getCodePointCount(),
-                probability, originalPtNode->getChildrenPos(), originalPtNode->getBigramsPos(),
-                originalPtNode->getShortcutPos(), &movedPos)) {
+        if (!writePtNodeToBufferByCopyingPtNodeInfo(originalPtNode, originalPtNode->getParentPos(),
+                codePoints, originalPtNode->getCodePointCount(), probability, &movedPos)) {
             return false;
         }
     }
@@ -259,9 +281,7 @@
             1 /* arraySize */, &writingPos)) {
         return false;
     }
-    if (!writeNodeToBuffer(false /* isBlacklisted */, false /* isNotAWord */, parentPtNodePos,
-            nodeCodePoints, nodeCodePointCount, probability, NOT_A_DICT_POS /* childrenPos */,
-            NOT_A_DICT_POS /* originalBigramsPos */, NOT_A_DICT_POS /* originalShortcutPos */,
+    if (!writePtNodeToBuffer(parentPtNodePos, nodeCodePoints, nodeCodePointCount, probability,
             &writingPos)) {
         return false;
     }
@@ -272,4 +292,69 @@
     return true;
 }
 
+// Returns whether the dictionary updating was succeeded or not.
+bool DynamicPatriciaTrieWritingHelper::reallocatePtNodeAndAddNewPtNodes(
+        const DynamicPatriciaTrieNodeReader *const reallocatingPtNode,
+        const int *const reallocatingPtNodeCodePoints, const int overlappingCodePointCount,
+        const int probabilityOfNewPtNode, const int *const newNodeCodePoints,
+        const int newNodeCodePointCount) {
+    // When addsExtraChild is true, split the reallocating PtNode and add new child.
+    // Reallocating PtNode: abcde, newNode: abcxy.
+    // abc (1st, not terminal) __ de (2nd)
+    //                         \_ xy (extra child, terminal)
+    // Otherwise, this method makes 1st part terminal and write probabilityOfNewPtNode.
+    // Reallocating PtNode: abcde, newNode: abc.
+    // abc (1st, terminal) __ de (2nd)
+    const bool addsExtraChild = newNodeCodePointCount > overlappingCodePointCount;
+    const int firstPtNodePos = mBuffer->getTailPosition();
+    if (!markNodeAsMovedAndSetPosition(reallocatingPtNode, firstPtNodePos)) {
+        return false;
+    }
+    int writingPos = firstPtNodePos;
+    // Write the 1st part of the reallocating node. The children position will be updated later
+    // with actual children position.
+    const int newProbability = addsExtraChild ? NOT_A_PROBABILITY : probabilityOfNewPtNode;
+    if (!writePtNodeToBuffer(reallocatingPtNode->getParentPos(), reallocatingPtNodeCodePoints,
+            overlappingCodePointCount, newProbability, &writingPos)) {
+        return false;
+    }
+    const int actualChildrenPos = writingPos;
+    // Create new children PtNode array.
+    const size_t newPtNodeCount = addsExtraChild ? 2 : 1;
+    if (!DynamicPatriciaTrieWritingUtils::writePtNodeArraySizeAndAdvancePosition(mBuffer,
+            newPtNodeCount, &writingPos)) {
+        return false;
+    }
+    // Write the 2nd part of the reallocating node.
+    if (!writePtNodeToBufferByCopyingPtNodeInfo(reallocatingPtNode,
+            reallocatingPtNode->getNodePos(),
+            reallocatingPtNodeCodePoints + overlappingCodePointCount,
+            reallocatingPtNode->getCodePointCount() - overlappingCodePointCount,
+            reallocatingPtNode->getProbability(), &writingPos)) {
+        return false;
+    }
+    if (addsExtraChild) {
+        if (!writePtNodeToBuffer(reallocatingPtNode->getNodePos(),
+                newNodeCodePoints + overlappingCodePointCount,
+                newNodeCodePointCount - overlappingCodePointCount, probabilityOfNewPtNode,
+                &writingPos)) {
+            return false;
+        }
+    }
+    if (!DynamicPatriciaTrieWritingUtils::writeForwardLinkPositionAndAdvancePosition(mBuffer,
+            NOT_A_DICT_POS /* forwardLinkPos */, &writingPos)) {
+        return false;
+    }
+    // Load node info. Information of the 1st part will be fetched.
+    DynamicPatriciaTrieNodeReader nodeReader(mBuffer, mBigramPolicy, mShortcutPolicy);
+    nodeReader.fetchNodeInfoFromBuffer(firstPtNodePos);
+    // Update children position.
+    int childrenPosFieldPos = nodeReader.getChildrenPosFieldPos();
+    if (!DynamicPatriciaTrieWritingUtils::writeChildrenPositionAndAdvancePosition(mBuffer,
+            actualChildrenPos, &childrenPosFieldPos)) {
+        return false;
+    }
+    return true;
+}
+
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
index 16b84ba..ebde24d 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
@@ -57,11 +57,19 @@
     bool markNodeAsMovedAndSetPosition(const DynamicPatriciaTrieNodeReader *const nodeToUpdate,
             const int movedPos);
 
-    bool writeNodeToBuffer(const bool isBlacklisted, const bool isNotAWord, const int parentPos,
-            const int *const codePoints, const int codePointCount, const int probability,
-            const int childrenPos, const int originalBigramListPos,
+    bool writePtNodeWithFullInfoToBuffer(const bool isBlacklisted, const bool isNotAWord,
+            const int parentPos,  const int *const codePoints, const int codePointCount,
+            const int probability, const int childrenPos, const int originalBigramListPos,
             const int originalShortcutListPos, int *const writingPos);
 
+    bool writePtNodeToBuffer(const int parentPos, const int *const codePoints,
+            const int codePointCount, const int probability, int *const writingPos);
+
+    bool writePtNodeToBufferByCopyingPtNodeInfo(
+            const DynamicPatriciaTrieNodeReader *const originalNode, const int parentPos,
+            const int *const codePoints, const int codePointCount, const int probability,
+            int *const writingPos);
+
     bool createAndInsertNodeIntoPtNodeArray(const int parentPos, const int *const nodeCodePoints,
             const int nodeCodePointCount, const int probability, int *const forwardLinkFieldPos);
 
@@ -74,6 +82,12 @@
 
     bool createNewPtNodeArrayWithAChildPtNode(const int parentPos, const int *const nodeCodePoints,
             const int nodeCodePointCount, const int probability);
+
+    bool reallocatePtNodeAndAddNewPtNodes(
+            const DynamicPatriciaTrieNodeReader *const reallocatingPtNode,
+            const int *const reallocatingPtNodeCodePoints, const int overlappingCodePointCount,
+            const int probabilityOfNewPtNode, const int *const newNodeCodePoints,
+            const int newNodeCodePointCount);
 };
 } // namespace latinime
 #endif /* LATINIME_DYNAMIC_PATRICIA_TRIE_WRITING_HELPER_H */
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_utils.cpp
index 4187504..b261e59 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_utils.cpp
@@ -68,11 +68,11 @@
     return buffer->writeUintAndAdvancePosition(nodeFlags, NODE_FLAG_FIELD_SIZE, nodeFlagsFieldPos);
 }
 
-/* static */ bool DynamicPatriciaTrieWritingUtils::writeParentPositionAndAdvancePosition(
-        BufferWithExtendableBuffer *const buffer, const int parentPosition,
+// Note that parentOffset is offset from node's head position.
+/* static */ bool DynamicPatriciaTrieWritingUtils::writeParentOffsetAndAdvancePosition(
+        BufferWithExtendableBuffer *const buffer, const int parentOffset,
         int *const parentPosFieldPos) {
-    // Note that parentPosition is offset from node's head position.
-    int offset = (parentPosition != NOT_A_DICT_POS) ? parentPosition : 0;
+    int offset = (parentOffset != NOT_A_DICT_POS) ? parentOffset : 0;
     return writeDictOffset(buffer, offset, parentPosFieldPos);
 }
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_utils.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_utils.h
index 801042d..183ede4 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_utils.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_utils.h
@@ -39,7 +39,7 @@
             const DynamicPatriciaTrieReadingUtils::NodeFlags nodeFlags,
             int *const nodeFlagsFieldPos);
 
-    static bool writeParentPositionAndAdvancePosition(BufferWithExtendableBuffer *const buffer,
+    static bool writeParentOffsetAndAdvancePosition(BufferWithExtendableBuffer *const buffer,
             const int parentPosition, int *const parentPosFieldPos);
 
     static bool writeCodePointsAndAdvancePosition(BufferWithExtendableBuffer *const buffer,
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp b/native/jni/src/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp
index 6326754..dfdaebd 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp
@@ -66,16 +66,17 @@
 
 bool BufferWithExtendableBuffer::checkAndPrepareWriting(const int pos, const int size) {
     if (isInAdditionalBuffer(pos)) {
-        if (pos == mUsedAdditionalBufferSize) {
+        const int tailPosition = getTailPosition();
+        if (pos == tailPosition) {
             // Append data to the tail.
-            if (pos + size > static_cast<int>(mAdditionalBuffer.size())) {
+            if (pos + size > static_cast<int>(mAdditionalBuffer.size()) + mOriginalBufferSize) {
                 // Need to extend buffer.
                 if (!extendBuffer()) {
                     return false;
                 }
             }
             mUsedAdditionalBufferSize += size;
-        } else if (pos + size >= mUsedAdditionalBufferSize) {
+        } else if (pos + size >= tailPosition) {
             // The access will beyond the tail of used region.
             return false;
         }